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Is exercise contagious? Yes, but in ways that might surprise you

Exercise is contagious

If you're involved in the marketing efforts of your business, you may be aware of influencer marketing, a practice where companies and brands focus on key leaders to drive your brand’s message to the larger market, often using social media. The ability of individuals to persuade and influence behavior by way of social channels is by no means limited to business, of course. Research shows how some "ordinary" individuals really can influence friends when it comes to specific activities.

For example, let's look at fitness. Between wearable devices and tracking apps, there are many methods with which to track, communicate, and share fitness accomplishments--or even just their daily activities. Fitbit has more than 23.2 million active users. RunKeeper claims it has 50 million runners. And Strava, a running and cycling tracker, reportedly has approximately 1.2 million active users (note: Strava does not release its numbers publicly). Clearly, lots of people, presumably across a wide range of demographics, use various fitness devices and apps on a regular basis.

One might assume that choosing to work out (or to not) is an individual decision based on motivation, training goals, how one is feeling that day, weather, and more. In a new study recently published in Nature Communications and widely covered by the New York Times, the LA Times, Runner’s World, and more, Sinan Aral, Professor of Information Technology and Marketing at MIT Sloan, proved that social networks can influence exercise routines.

The research project included a collaboration with a fitness device maker to better understand the influence of social networks on activity. By taking activity data and overlaying it with both weather data and social network information, Aral was able to deduce that less active people had a bigger influence on their friends than those who were very active, like marathon runners.

One might think this is counter intuitive; that the marathoners would have more influence over the more casual runner. But here's what Aral found in the data. Say you are a marathon runner in Arizona. You have a friend who is, essentially, a couch potato in New York. You see on a social network that your couch potato friend went off for a nice long run earlier today, despite the fact that it was raining in New York. So instead of skipping your planned work out, you think: I can’t let my couch potato friend lap me; so I'm hitting the pavement. One would naturally think that the marathoner has more influence over the couch potato. But Aral's research proves otherwise.

On this topic, Aral co-authored a paper, "Engineering Social Contagions: Optimal Network Seeding in the Presence of Homophily," that recently won the Network Science Best Paper Award, sponsored by the Indiana University Network Science Institute. This first-ever award was chosen by the editors from all papers published in the first four volumes of the journal, from 2013 to 2016.

Sinan Aral is Professor of Information Technology and Marketing at MIT Sloan. He teaches in the Executive Education program, Digital Marketing and Social Media Analytics.


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